Copper Nickel Composite Weld Neck Flanges
HC manufactures Copper Nickel Composite Weld Neck Flanges for marine, offshore, shipbuilding, desalination and seawater piping systems.
As a manufacturer, HC can produce Copper Nickel Composite Weld Neck Flanges according to ASME, EN, DIN, JIS standards or customer drawings. Common collar materials include C70600 CuNi 90/10 and C71500 CuNi 70/30. Backing flanges can be supplied in carbon steel, stainless steel, galvanized steel or coated steel according to project specifications.
- Copper nickel weld neck collar / innner flange
- Loose backing flange
- Collar welded with copper nickel pipe
- Backing flange provides bolting pressure
- Backing flange does not contact the media
HC also supplies matching copper nickel piping products, including Copper Nickel Pipes, Copper Nickel Pipe Fittings, Copper Nickel Flanges and Copper Nickel Butt Weld Fittings.
What Is a Copper Nickel Composite Weld Neck Flange?
A copper nickel composite weld neck flange consists of two main parts: a copper nickel collar and a loose backing flange.
Copper Nickel Collar / Inner Flange
The collar is made from copper nickel alloy and welded to the copper nickel pipe. It forms the sealing face and is the only part exposed to seawater or other corrosive media.
Backing Flange / Loose Flange
The backing flange is usually made from carbon steel, stainless steel or coated steel. It provides the mechanical strength for bolting and tightening. Since it does not touch the medium, it can be made from a more economical material.
This structure gives the flange both corrosion resistance and cost efficiency, making it a practical choice for large-scale seawater pipeline projects.
Unlike a solid copper nickel flange, the backing flange does not contact the fluid medium. The sealing surface is located on the copper nickel collar, which helps reduce material cost while maintaining excellent corrosion resistance where it matters most.
Copper Nickel Composite Weld Neck Flanges Specifications
HC manufactures Copper Nickel Composite Weld Neck Flanges in standard and customized dimensions. Material grade, pressure rating, drilling pattern, sealing face and surface treatment can be produced according to project requirements.
| Product Name | Copper Nickel Composite Weld Neck Flanges |
| Manufacturer | HC |
| Product Structure | Copper nickel weld neck collar / inner flange + loose backing flange |
| Collar Material | C70600, C71500, CuNi 90/10, CuNi 70/30 or as specified |
| Backing Flange Material | Carbon steel, stainless steel, galvanized steel, coated steel or customized material |
| Connection Type | Weld neck collar with loose backing flange |
| Sealing Surface | Copper nickel collar sealing face |
| Media Contact Area | Only the copper nickel collar contacts the medium; the backing flange does not contact the media |
| Standards | ASME B16.5, EEMUA, DIN, JIS or according to customer drawings |
| Pressure Rating | Class 150, Class 300, PN10, PN16, PN25, PN40 or customized |
| Size Range | Standard sizes and customized sizes available according to project requirements |
| Flange Face Type | Raised face, flat face or customized sealing face design |
| Backing Flange Surface Treatment | Anti-rust oil, black painting, galvanized coating, epoxy coating or as required |
| Inspection | Material certificate review, dimensional inspection, visual inspection, flange drilling inspection, sealing face inspection, PMI test if required |
| Application | Marine seawater systems, offshore platforms, shipbuilding, desalination plants, heat exchangers, cooling water systems, ballast systems and firewater systems |
| Customization | HC can manufacture according to drawings, technical specifications and project standards |
| Packing | Wooden cases, pallets or seaworthy export packing |
Why Choose Copper Nickel Composite Weld Neck Flanges?
Copper Nickel Composite Weld Neck Flanges offer a balanced solution for corrosion resistance, installation convenience and project cost control.
Excellent Seawater Corrosion Resistance
Copper nickel alloys such as C70600 CuNi 90/10 and C71500 CuNi 70/30 are widely used in marine engineering because they resist seawater corrosion, biofouling and erosion. The copper nickel collar protects the wetted area of the flange, helping extend the service life of the piping system.
Lower Cost Than Solid Copper Nickel Flanges
Because the backing flange does not contact the medium, it does not need to be made from copper nickel. This reduces the total use of copper nickel material and helps control project cost, especially for large-diameter flange systems.
Easy Alignment During Installation
The loose backing flange can rotate freely before bolting. This makes bolt hole alignment easier during installation, especially in shipboard piping, offshore modules and confined working spaces.
Reliable Welding Connection
The weld neck collar is welded directly to the copper nickel pipe, providing a strong and stable connection. This design is suitable for pressure piping systems where welding quality and sealing performance are important.
Suitable for Marine and Offshore Service
Copper nickel composite weld neck flanges are commonly used in seawater cooling systems, ballast systems, firewater systems, bilge systems and desalination pipelines.
Flexible Material Combination
The copper nickel collar can be supplied in C70600 or C71500, while the backing flange can be made from carbon steel, stainless steel, galvanized steel or other specified materials according to project requirements.
Copper nickel composite weld neck flanges are often selected when a project requires corrosion resistance on the wetted surface but also needs better cost control. The copper nickel collar ensures compatibility with copper nickel pipes, while the loose backing flange provides bolting strength without being exposed to the medium.
This design is especially useful for seawater piping systems where large quantities of flanges are required. Compared with solid copper nickel flanges, composite flanges can help reduce procurement cost while keeping the sealing and wetted areas protected by copper nickel alloy.
Marine Flanges Available Copper Nickel Materials
We manufacture Copper Nickel Composite Weld Neck Flanges using multiple copper nickel grades to meet different seawater systems, marine engineering, offshore, and industrial piping requirements.
CuNi 90/10 (UNS C70600)
CuNi 90/10 provides an excellent balance of corrosion resistance, weldability, mechanical strength, and cost efficiency. It is one of the most widely used copper nickel alloys for commercial marine piping systems.
Typical Applications
- Shipbuilding
- HVAC seawater systems
- Firefighting pipelines
- Heat exchangers
- Cooling water systems
For matching piping products, please visit Copper Nickel Pipes and Copper Nickel Butt Weld Fittings.
CuNi 70/30 (UNS C71500)
CuNi 70/30 contains a higher nickel content, offering superior resistance to seawater corrosion, erosion, and biofouling in demanding offshore environments.
Recommended Applications
- Naval vessels
- Offshore platforms
- Desalination plants
- High-flow seawater pipelines
- Condenser systems
Learn more about our 70/30 Copper Nickel Pipe and Copper Nickel Elbows to build a complete piping solution.
Copper Nickel Flanges Chemical Composition
90/10 (UNS C70600) Copper Nickel Flanges Chemical Composition
| KME CuNi90/10 | DIN 17664 2.0882 | BS 2871 CN102 | ASTM B466 C70600 | JIS H3300 C7060T | DIN 86019 2.1972 | EEMUA 234 UNS 7060X | GB/T 5231 BFe10-1.6-1 | |
| Ni% | 10.0-11.0 | 9.0-11.0 | 10.0-11.0 | 9.0-11.0 | 9.0-11.0 | 9.0-11.0 | 10.0-11.0 | 9.0-11.0 |
| Fe% | 1.5-1.8 | 1.0-2.0 | 1.0-2.0 | 1.0-1.8 | 1.0-1.8 | 1.5-1.8 | 1.5-2.0 | 1.5-1.8 |
| Mn% | 0.6-1.0 | 0.5-1.0 | 0.5-1.0 | max.1.0 | 0.2-1.0 | 0.5-1.0 | 0.5-1.0 | 0.5-1.0 |
| C% | max.0.05 | max.0.05 | max.0.05 | max.0.05 | max.0.05 | max.0.05 | max.0.05 | |
| Pb% | max.0.01 | max.0.03 | max.0.01 | max.0.02 | max.0.05 | max.0.01 | max.0.01 | max.0.03 |
| S% | max.0.005 | max.0.02 | max.0.05 | max.0.02 | max.0.005 | max.0.02 | max.0.01 | |
| P% | max.0.02 | max.0.02 | max.0.02 | max.0.02 | max.0.02 | max.0.02 | ||
| Zn% | max.0.05 | max.0.50 | max.0.50 | max.0.50 | max.0.05 | max.0.20 | max.0.20 | |
| Other | max.0.20 | max.0.30 | max.0.20 | max.0.30 | max.0.40 | |||
| Cu% | rem. | rem. | rem. | rem. | +Ni+Fe+Mn min99.5 | rem. | rem. | rem. |
70/30 (UNS C71500) Copper Nickel Flanges Chemical Composition
| KME CuNi70/30 | DIN 176642.0882 | BS 2871 CN107 | ASTM B466C71500 | JIS H3300C7150T | |
| Ni% | 30.0-32.0 | 30.0-32.0 | 30.0-32.0 | 29.0-33.0 | 29.0-33.0 |
| Fe% | 0.47-0.7 | 0.4-1.0 | 0.4-1.0 | 0.4-1.0 | 0.4-1.0 |
| Mn% | 0.5-1.0 | 0.5-1.5 | 0.5-1.5 | max.1.0 | 0.2-1.0 |
| C% | max.0.04 | max.0.05 | max.0.06 | max.0.05 | |
| Pb% | max.0.01 | max.0.03 | max.0.01 | max.0.02 | max.0.05 |
| S% | max.0.01 | max.0.02 | max.0.08 | max.0.02 | |
| P% | max.0.02 | max.0.02 | max.0.02 | ||
| Zn% | max.0.20 | max.0.50 | max.0.50 | max.0.50 | |
| Other | max.0.30 | max.0.30 | |||
| Cu% | rem. | rem. | rem. | rem. | +Ni+Fe+Mn min99.5 |
Applications of Copper Nickel Composite Weld Neck Flanges
Copper Nickel Composite Weld Neck Flanges are used in many industries where seawater corrosion resistance and reliable piping connections are required.
- Shipbuilding seawater pipeline systems
- Offshore oil and gas platforms
- Marine cooling water systems
- Firewater and ballast water systems
- Desalination plants
- Heat exchanger piping
- Coastal power plants
- Chemical and petrochemical marine facilities
- Naval and commercial vessel piping systems
For complete system supply, we can provide matching Copper Nickel Elbows, Copper Nickel Tees and Copper Nickel Reducers.
Marine Flanges Copper Nickel Packaging & Quality Control
Marine Flanges Copper Nickel Packaging
Products are securely packed for international transportation using export-grade packaging to minimize handling damage during long-distance shipment.
- Fumigation-free plywood cases
- Wooden export crates
- Steel pallet packaging
- Moisture-proof protection
- Customized export packaging available
Marine Flanges Copper Nickel Quality Control
Every Copper Nickel Composite Weld Neck Flange is manufactured under strict quality management procedures to ensure reliable performance in marine and offshore piping systems. Particular attention is paid to the concentricity between the copper nickel collar and the backing flange, ensuring accurate installation and dependable sealing.
Every production batch can be inspected according to customer specifications. Inspection reports and material certificates are available before shipment.
- PMI (Positive Material Identification)
- Chemical composition analysis
- Dimensional inspection
- Surface quality inspection
- Mechanical property testing
- Hydrostatic testing (when required)
- Third-party inspection (SGS, BV, DNV, LR, ABS)
Material Test Certificates EN 10204 3.1 / 3.2 are available upon request.
Why Choose HC as Your Copper Nickel Flange Supplier?
HC has extensive experience supplying copper nickel piping products to customers worldwide. From marine seawater systems to offshore and industrial piping projects, we support buyers with stable manufacturing capability, technical service and complete export solutions.
HC Manufacturing Advantages
- Complete range of CuNi 90/10 & CuNi 70/30 products
- Precision CNC machining
- Strict quality management
- Custom manufacturing services
- Fast global delivery
- Competitive factory pricing
- Professional technical support
- Complete export documentation
One-Stop Copper Nickel Piping Solution
Whether your project requires individual Copper Nickel Composite Weld Neck Flanges or a complete copper nickel piping system, HC can provide a one-stop solution for marine and industrial applications.
Our supply range includes Copper Nickel Pipes, Copper Nickel Composite Slip On Flanges , Copper Nickel Elbows, Copper Nickel Tees, and other Copper Nickel Butt Weld Fittings.
Need Recommendation?
Send HC your flange size, standard, pressure rating, material grade and quantity. Drawings or technical specifications are also welcome.
Contact HC for a QuoteFrequently Asked Questions – Copper Nickel Composite Weld Neck Flange
What is a Copper Nickel Composite Weld Neck Flange?
A Copper Nickel Composite Weld Neck Flange consists of a corrosion-resistant copper nickel collar and a carbon steel backing flange. The copper nickel collar comes into contact with the process medium and provides excellent seawater corrosion resistance, while the carbon steel backing flange delivers mechanical strength and simplifies installation.
Why use a composite flange instead of a solid copper nickel flange?
Composite flanges offer the same corrosion-resistant sealing surface as solid copper nickel flanges while significantly reducing material costs. Since only the wetted component is manufactured from copper nickel alloy, they provide an economical solution without compromising performance.
Can the backing flange rotate?
Yes. The loose carbon steel backing flange can rotate freely after the copper nickel collar has been welded to the pipe, allowing quick and accurate bolt-hole alignment during installation and maintenance.
Which copper nickel alloy is better: CuNi 90/10 or CuNi 70/30?
CuNi 90/10 (C70600) is widely used for general seawater piping systems because of its excellent corrosion resistance and cost efficiency. CuNi 70/30 (C71500) provides even greater resistance to erosion-corrosion and biofouling, making it ideal for high-velocity seawater, offshore platforms, naval vessels, and other demanding marine environments.
Can you manufacture composite weld neck flanges according to customer drawings?
Yes. We manufacture Copper Nickel Composite Weld Neck Flanges according to international standards such as ASME, EN, DIN, and JIS, as well as custom technical drawings and project specifications.
Does the backing flange come into contact with seawater?
No. The copper nickel collar forms the sealing surface and isolates the process medium. The carbon steel backing flange remains outside the wetted area, allowing the assembly to maintain excellent corrosion resistance while reducing overall material costs.
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